Speaker Rajesh Balan
Affiliation Singapore Management University
Host Sharad Agarwal
Date recorded 4 December 2012
In this talk, I will show that it is possible to reduce the display power consumption of LCD-based devices by up to 35 to 40% with no noticeable impact on end user performance. If some amount of tolerable degradation is possible, the power savings can be as high as 70%.
The key insight behind our techniques is that we use tone mapping techniques to dynamically increase the image brightness, thus allowing the LCD backlight levels to be reduced. This saves significant power as the majority of the LCD's display power is consumed by its backlight. The Gamma function (or equivalent) can be efficiently implemented in smartphones with minimal resource cost. I describe how we overcame the Gamma function's non-linear nature by using adaptive thresholds to apply different Gamma values to images with differing brightness levels. These adaptive thresholds allow us to save significant amounts of power while preserving the image quality.
Our solution has been implemented on laptops, Android phones and tablets, and even on consumer grade 42 inch TVs. I will present measured analytical results for two different games (Quake III and Planeshift), and user study results (using Quake III and 60 participants) that shows that we can save up to 35 to 40% of the display power with no user-noticeable impact and that we can save up to 70% of the display power if we are willing to accept a reasonable amount of image degradation.
At the talk, I will have a live interactive demo of the system running on both a laptop and an Android tablet that attendees can play with and see how the techniques work on real systems with a real game (Quake III).
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